Printing devices often include resource units. Such resource units are designed to be periodically replaced. Some replaceable resource units can be refurbished in some manner and reused. Most replaceable resources have limited lifetimes due to normal wear, etc. Unfortunately, it can be difficult to identify how much, how often and/or for how long a replaceable resource unit has been used. Such determinations would be useful, for example, when addressing warranty issues associated with the printing device and/or replaceable resource, purchasing refurbished units, and/or at other times.